This invention relates to incandescent lighting structures that achieve multifold increase in efficiency as compared to standard incandescent light bulbs.
Incandescent light bulbs [1] are the most common source of everyday lighting during the modern era. Unfortunately, incandescent light bulbs are not very efficient. Typically only 2-5% of electrical power ends up in the visible spectrum. The rest is wasted, mostly by radiation into infra-red (IR), and some is also lost into heat. Since close to 25% of generated electrical energy is used for lighting, there are large opportunities for saving power by moving to more efficient light sources: plausible alternatives include fluorescent lighting and LED lighting. In fact, this consideration has already given rise to laws in most major developed economies in Europe, Australia, and US, mandating increased efficiencies for lighting. However, remaining challenges with higher-efficiency lighting offerings include higher fabrication costs, limits to wall-plug efficiency arising from various loss mechanisms, and quality of lighting provided, as measured by the correlated color temperature (CCT) and color rendering index (CRI).
An alternative approach lies in using novel nanophotonic techniques to modify the emission spectrum of a thermal source to something tailored for a particular application [2]. For example, novel nanophotonic mirrors [3, 4] have been discovered that can have properties that dramatically surpass conventional mirrors. Such mirrors can be designed to surround a thermal emitter in order to recycle IR radiation back to its source. Additional, novel nanostructured thermal emitters can be used to directly radiate light at target wavelengths of interest, while suppressing other wavelengths of less relevance.